JPH0658444B2 - Fiber type optical wavelength filter - Google Patents
Fiber type optical wavelength filterInfo
- Publication number
- JPH0658444B2 JPH0658444B2 JP60270695A JP27069585A JPH0658444B2 JP H0658444 B2 JPH0658444 B2 JP H0658444B2 JP 60270695 A JP60270695 A JP 60270695A JP 27069585 A JP27069585 A JP 27069585A JP H0658444 B2 JPH0658444 B2 JP H0658444B2
- Authority
- JP
- Japan
- Prior art keywords
- core
- refractive index
- optical wavelength
- fiber
- wavelength filter
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Classifications
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/24—Coupling light guides
- G02B6/26—Optical coupling means
- G02B6/28—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals
- G02B6/293—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals with wavelength selective means
- G02B6/29331—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals with wavelength selective means operating by evanescent wave coupling
- G02B6/29332—Wavelength selective couplers, i.e. based on evanescent coupling between light guides, e.g. fused fibre couplers with transverse coupling between fibres having different propagation constant wavelength dependency
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- Optical Fibers, Optical Fiber Cores, And Optical Fiber Bundles (AREA)
- Light Guides In General And Applications Therefor (AREA)
- Optical Filters (AREA)
Description
【発明の詳細な説明】 ［産業上の利用分野］ 本発明は、小型に構成され、しかも高性能で可撓性に富
み、光ファイバとの接続が容易なファイバ形光波長フィ
ルタに関するものである。Description: TECHNICAL FIELD The present invention relates to a fiber type optical wavelength filter which is small in size, has high performance, is highly flexible, and can be easily connected to an optical fiber. .
［従来の技術］ 従来、光フィルタとしては、ファブリ・ペロー板が知ら
れている。ファブリ・ペロー板はMgF2（フッ化マグネシ
ウム）の薄層の両面に銀付けして、エネルギー反射率を
95％位にしたものであり、MgF2の厚さを希望波長λｓの
1/4程度にすることによって透過光の波長幅が数Å〜数
百Å程度のフィルタが得られる。[Prior Art] Conventionally, a Fabry-Perot plate is known as an optical filter. The Fabry-Perot plate is silvered on both sides of a thin layer of MgF 2 (magnesium fluoride) to increase the energy reflectivity.
It is about 95%, and the thickness of MgF 2 is
By making it about 1/4, a filter with a wavelength width of transmitted light of several Å to several hundred Å can be obtained.
このようなファブリ・ペロー板の他にも、複屈折性の結
晶、たとえば水晶または雲母等を用いたフィルタが知ら
れている。In addition to such a Fabry-Perot plate, a filter using a birefringent crystal such as quartz or mica is known.
しかし、従来のこれらの光フィルタはバルク形であるの
で、光ファイバとの接続に際しては、レンズや微動台等
の光学装置を必要とし、したがって振動に弱く、しかも
また、装置を小型化，軽量化できないという欠点があっ
た。However, since these conventional optical filters are of bulk type, they require an optical device such as a lens or a fine movement table when connecting with an optical fiber, and are therefore susceptible to vibration, and the device can be made smaller and lighter. There was a drawback that I could not.
［発明が解決しようとする問題点］ そこで、本発明の目的は、従来のこのような欠点を解決
した小型かつ高性能のファイバ形光波長フィルタを提供
することにある。[Problems to be Solved by the Invention] Therefore, an object of the present invention is to provide a small-sized and high-performance fiber-type optical wavelength filter which solves the above-mentioned conventional drawbacks.
［問題点を解決するための手段］ このような目的を達成するために、本発明は、屈折率が
ｎＣなるクラッド中に、屈折率がそれぞれｎ１およびｎ
２なる第１および第２コアを離隔配置し、第１および第
２コアのうち屈折率の大きい方のコアを、屈折率ｎＣよ
り小さい屈折率を有する低屈折率層で取り囲んで配置し
たことを特徴とする。[Means for Solving Problems] In order to achieve such an object, according to the present invention, in a clad having a refractive index of n C , the refractive indices are n 1 and n, respectively.
2 becomes the first and second cores spaced apart, the core of the larger refractive index of the first and second cores, and arranged surrounding at low refractive index layer having a refractive index n C of less than the refractive index Is characterized by.
［作用］ 本発明光波長フィルタは、総て光ファイバで構成される
ので、従来の波長フィルタとは異なり、伝送路用の単一
モード光ファイバとの接続が極めて容易であり、しかも
その接続を低損失で行うことができる。[Operation] Since the optical wavelength filter of the present invention is composed entirely of optical fibers, unlike conventional wavelength filters, it is extremely easy to connect to a single-mode optical fiber for a transmission line, and the connection is It can be done with low loss.
［実施例］ 以下に、図面を参照して本発明を詳細に説明する。[Examples] Hereinafter, the present invention will be described in detail with reference to the drawings.
第１図は、本発明の一実施例を示す。第１図において、
１は屈折率がｎ１なるコア、２は屈折率がｎ２なるコア
であり、両コア１と２とを互いに平行に配置する。これ
らコア１および２の屈折率は、 ｎ１＜ｎ２ (1) なる条件を満足するものとする。３はコア１と２を取り
囲んで配置され、屈折率がｎＣなるクラッドである。さ
らに、コア２は屈折率がｎ′ある低屈折率層４で囲まれ
ており、ここで、ｎ′は、 ｎ′＜ｎＣ (2) なる条件を満足するものとする。FIG. 1 shows an embodiment of the present invention. In FIG.
Reference numeral 1 denotes a core having a refractive index of n 1 , 2 denotes a core having a refractive index of n 2 , and both cores 1 and 2 are arranged in parallel with each other. The refractive indices of the cores 1 and 2 satisfy the condition of n 1 <n 2 (1). Reference numeral 3 is a clad that surrounds the cores 1 and 2 and has a refractive index of n C. Further, the core 2 is surrounded by the low refractive index layer 4 having a refractive index of n ', where n'satisfys the condition of n'<n C (2).
第２図(A)はかかる実施例におけるコア部分の断面の詳
細を示し、第２図(B)は第２図(A)に対応して屈折率分布
を示す図である。FIG. 2 (A) shows details of the cross section of the core portion in such an embodiment, and FIG. 2 (B) is a view showing the refractive index distribution corresponding to FIG. 2 (A).
ここで、コア１の直径は2a1、コア２の直径は2a2、低屈
折率層４の厚さはｔであり、コア１とコア２の中心間距
離はｄである。Here, the diameter of the core 1 is 2a 1 , the diameter of the core 2 is 2a 2 , the thickness of the low refractive index layer 4 is t, and the center-to-center distance between the core 1 and the core 2 is d.
以下の説明の便宜上、次のパラメータを定義する。For convenience of the following description, the following parameters are defined.
このようにデュアルコアファイバを有する本発明のファ
イバ形光波長フィルタはたとえば第３図の作成方法によ
って形成できる。 Thus, the fiber type optical wavelength filter of the present invention having the dual core fiber can be formed, for example, by the manufacturing method shown in FIG.
第３図において、超音波ドリルで穴開けしたプリフォー
ム10に、コア１のためのプリフォーム11およびコア２の
ためのプリフォーム12と低屈折率層４のためのプリフォ
ーム13とを挿通した他のプリフォーム14を挿入したもの
をヒータ15に通し、ここで、たとえば2100℃に加熱し
て、矢印方向に線引きすることによって第１図示のデユ
アルコアファイバ構成が得られる。In FIG. 3, a preform 11 for the core 1, a preform 12 for the core 2 and a preform 13 for the low refractive index layer 4 were inserted into a preform 10 that was ultrasonically drilled. The insert of another preform 14 is passed through a heater 15, where it is heated to, for example, 2100 ° C. and drawn in the direction of the arrow to obtain the dual core fiber structure shown in FIG.
次に、第１図示の光波長フィルタの動作について説明す
る。第１図に示すように、コア１に強度Pi（λ）の光が
入射したときのコア１とコア２との間のモード結合を考
える。ここで、λは光の波長である。Next, the operation of the optical wavelength filter shown in FIG. 1 will be described. As shown in FIG. 1, consider mode coupling between core 1 and core 2 when light of intensity Pi (λ) enters core 1. Here, λ is the wavelength of light.
平行コア間のモード結合に関しては、A.W.Snyderによる
“Coupled-mode theory for optical fibers”(Jour.o
f.Opt,Soe.Am.,vol.62，no.11，p.1267，1972)に詳しく
述べられている。Regarding mode coupling between parallel cores, AWSnyder's “Coupled-mode theory for optical fibers” (Jour.o
f.Opt, Soe.Am., vol.62, no.11, p.1267, 1972).
かかるディアルコアファイバの長さがであるとき、コ
ア１およびコア２からの出射光強度は、それぞれ、 で与えられる。ただし、ここで、 であり、ＫｏはＯ次の第二種変形ベッセル関数，β１お
よびβ２は各々コア１およびコア２の伝搬定数である。
式(9)において、ηは次式で与えられる。When the length of such a dual-core fiber is, the output light intensity from the core 1 and the core 2 is, Given in. However, here Where Ko is the modified Bessel function of the second kind of the Oth order, and β 1 and β 2 are the propagation constants of the core 1 and the core 2, respectively.
In equation (9), η is given by the following equation.
次に、コア１およびコア２への各透過率Ｓ（λ）および
Ｔ（λ）を以下のように定義する。 Next, the transmittances S (λ) and T (λ) to the core 1 and the core 2 are defined as follows.
ここで、たとえばΔ１＝0.25％，Δ２＝0.4％，Δ′＝
−0.3％，Ｈ＝0.6，ｄ＝4a1，ａ１＝4.1μｍ，ａ２＝4.
1μｍ，ａ２＝3.1μｍ，ｔ＝4.7μｍのときの各透過率
Ｓ（λ）およびＴ（λ）を、それぞれ、第４図および第
５図に示す。ここで透過波長はλｏ＝1.296μｍであ
る。 Here, for example, Δ 1 = 0.25%, Δ 2 = 0.4%, Δ ′ =
-0.3%, H = 0.6, d = 4a 1 , a 1 = 4.1 μm, a 2 = 4.
The transmittances S (λ) and T (λ) at 1 μm, a 2 = 3.1 μm, and t = 4.7 μm are shown in FIGS. 4 and 5, respectively. Here, the transmission wavelength is λ o = 1.296 μm.
第４図および第５図より、コア１に光が入射した場合、
コア１の出力特性は帯域阻止フィルタ特性となり、他
方、コア２の出力特性は帯域通過フィルタ特性となるこ
とが分かる。From FIG. 4 and FIG. 5, when light is incident on the core 1,
It can be seen that the output characteristic of the core 1 becomes a band stop filter characteristic, while the output characteristic of the core 2 becomes a band pass filter characteristic.
フィルタとしての半値全幅FWHM(Full Width at Half Ma
ximum)は、これら帯域阻止フィルタおよび帯域通過フィ
ルタのいずれにおいても δλ＝6.4［ｎｍ］ (21) である。光波長フィルタの性能は半値全幅で評価され、
その値が小さい程良好なフィルタとなる。FWHM (Full Width at Half Ma) as a filter
ximum) is δλ = 6.4 [nm] (21) in both the band stop filter and the band pass filter. The performance of the optical wavelength filter is evaluated at full width at half maximum,
The smaller the value, the better the filter.
コア１およびコア２の導波構造パラメータを変えて半値
全幅を計算した結果を第６図〜第８図に示す。The results of calculating the full width at half maximum by changing the waveguide structure parameters of the core 1 and the core 2 are shown in FIGS. 6 to 8.
第６図は、コア２のコア半径ａ（＝ａ２＋ｔ）と低屈折
率層の厚さｔとの比Ｈ（＝ｔ／ａ）に対する半値全幅δ
λの変化を示したものである。なお、コア１の遮断波長
はλC1＝1.1μｍ、透過波長はλｏ＝1.296μｍに保たれ
ており、Ｈの変化に対応するコア２の遮断波長λC2の変
化も図示されている。FIG. 6 shows the full width at half maximum δ with respect to the ratio H (= t / a) of the core radius a (= a 2 + t) of the core 2 and the thickness t of the low refractive index layer.
This shows the change in λ. The cutoff wavelength of the core 1 is kept at λ C1 = 1.1 μm and the transmission wavelength is kept at λ o = 1.296 μm, and the change of the cutoff wavelength λ C2 of the core 2 corresponding to the change of H is also shown.
同様にして、第７図はコア２の屈折率差Δ２の変化に対
するδλの変化を示し、第８図は低屈折率層の屈折率差
Δ′の変化に対するδλの変化を示す。Similarly, FIG. 7 shows the change of δλ with respect to the change of the refractive index difference Δ 2 of the core 2, and FIG. 8 shows the change of δλ with respect to the change of the refractive index difference Δ ′ of the low refractive index layer.
第６図から、δλはＨの増加とともに小さくなることが
分かる。また、第７図から、Δ２を大きくしてもδλは
余り小さくならないことをが分かる。さらに、第８図よ
りΔ′は小さい程δλを小さくできることが分かる。From FIG. 6 it can be seen that δλ decreases with increasing H. Further, it can be seen from FIG. 7 that δλ does not become so small even if Δ 2 is increased. Further, it can be seen from FIG. 8 that δλ can be made smaller as Δ ′ is smaller.
なお、以上の実施例では、透過波長をλｏ＝1.296μｍ
に定めたが、ディアルコアファイバの結合係数Ｋ（具体
的には、屈折率差、コア径、およびコア間距離）やデュ
アルコアファイバの長さを適当に選ぶことによって所
望の波長にすることができること勿論である。In the above embodiment, the transmission wavelength is λo = 1.296 μm.
However, the desired wavelength can be achieved by appropriately selecting the coupling coefficient K (specifically, the refractive index difference, the core diameter, and the distance between the cores) of the dual core fiber and the length of the dual core fiber. Of course.
［発明の効果］ 以上説明したように、本発明によれば、高性能で小型に
構成され、しかも他の光ファイバとの接続が容易な光波
長フィルタを実現することができる。しかもまた、光フ
ァイバは曲げ直径３cm程度まで曲げてもその特性は変化
しないので、本発明のファイバ光波長フィルタは可撓性
に富むという大きな特長がある。[Effects of the Invention] As described above, according to the present invention, it is possible to realize an optical wavelength filter that is configured with high performance and a small size, and that can be easily connected to other optical fibers. Moreover, since the characteristics of the optical fiber do not change even when bent to a bending diameter of about 3 cm, the fiber optical wavelength filter of the present invention has a great feature of being highly flexible.
【図面の簡単な説明】 第１図は本発明の一実施例を示す斜視図、 第２図(A)はその詳細部分を示す断面図、 第２図(B)は第２図(A)に対応して屈折率分布を示す分布
図、 第３図は本実施例におけるデユアルコアファイバの作製
例を示す斜視図、 第４図はコア１に光が入射したときのコア１への光の透
過率を示す特性図、 第５図はコア１に光が入射したときのコア２への光の透
過率を示す特性図、 第６図はコア２のファイバパラメータＨを変化させたと
きのδλの変化を示す特性図、 第７図はコア２のファイバパラメータΔ２を変化させた
ときのδλの変化を示す特性図、 第８図はコア２のファイバパラメータΔ′を変化させた
ときのδλの変化を示す特性図である。 １……コア、 ２……コア、 ３……クラッド、 ４……低屈折率層、 10〜14……プリフォーム、 15……ヒータ。BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view showing an embodiment of the present invention, FIG. 2 (A) is a sectional view showing a detailed portion thereof, and FIG. 2 (B) is FIG. 2 (A). FIG. 3 is a distribution diagram showing a refractive index distribution corresponding to FIG. 3, FIG. 3 is a perspective view showing a production example of the dual core fiber in the present embodiment, and FIG. 4 is a diagram showing the light to the core 1 when the light is incident on the core 1. FIG. 5 is a characteristic diagram showing the transmittance, FIG. 5 is a characteristic diagram showing the light transmittance to the core 2 when the light is incident on the core 1, and FIG. 6 is δλ when the fiber parameter H of the core 2 is changed. characteristic diagram showing a change in, FIG. 7 is a characteristic diagram showing a change in [delta] [lambda] when changing the fiber parameters delta 2 of the core 2, [delta] [lambda] when FIG. 8 is obtained by changing the fiber parameters delta 'of the core 2 It is a characteristic view showing the change of. 1 ... Core, 2 ... Core, 3 ... Clad, 4 ... Low refractive index layer, 10-14 ... Preform, 15 ... Heater.
Claims (1)
それぞれｎ１およびｎ２なる第１および第２コアを離隔
配置し、前記第１および第２コアのうち屈折率の大きい
方のコアを、屈折率ｎＣより小さい屈折率を有する低屈
折率層で取り囲んで配置したことを特徴とするファイバ
形光波長フィルタ。1. A clad having a refractive index of n C , wherein first and second cores having refractive indices of n 1 and n 2 are spaced apart from each other, and one of the first and second cores having a larger refractive index is provided. A fiber type optical wavelength filter, characterized in that the core is surrounded by a low refractive index layer having a refractive index smaller than a refractive index n C.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP60270695A JPH0658444B2 (en) | 1985-12-03 | 1985-12-03 | Fiber type optical wavelength filter |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP60270695A JPH0658444B2 (en) | 1985-12-03 | 1985-12-03 | Fiber type optical wavelength filter |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS62131204A JPS62131204A (en) | 1987-06-13 |
| JPH0658444B2 true JPH0658444B2 (en) | 1994-08-03 |
Family
ID=17489668
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP60270695A Expired - Fee Related JPH0658444B2 (en) | 1985-12-03 | 1985-12-03 | Fiber type optical wavelength filter |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0658444B2 (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH02212803A (en) * | 1989-02-14 | 1990-08-24 | Fujikura Ltd | Optical fiber wavelength filter |
| US7424193B2 (en) * | 2004-07-14 | 2008-09-09 | The Regents Of The University Of Michigan | Composite waveguide |
| US9574911B2 (en) * | 2012-08-09 | 2017-02-21 | Corning Incorporated | Two-core optical fibers for distributed fiber sensors and systems |
-
1985
- 1985-12-03 JP JP60270695A patent/JPH0658444B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPS62131204A (en) | 1987-06-13 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN110618487B (en) | Multimode interference type polarization insensitive power divider based on sub-wavelength grating structure | |
| US4839898A (en) | Optical resonating device | |
| JP2644060B2 (en) | Adiabatic polarization control device | |
| JPS59148005A (en) | Optical fiber for propagating single mode single polarized wave | |
| JPH0563763B2 (en) | ||
| JPH0658444B2 (en) | Fiber type optical wavelength filter | |
| JPS583205B2 (en) | Ultra-wideband single mode optical fiber | |
| CN206573739U (en) | A kind of reflection-type narrow band filter based on waveguide bragg grating | |
| WO2004074893A1 (en) | Add-drop wavelength filter using mode discrimination couplers and tilted bragg gratings | |
| JP3784593B2 (en) | Single / multimode optical fiber coupler and method of manufacturing the same | |
| CN110673259A (en) | A cascaded chirped long-period fiber grating bandpass filter | |
| JP2764263B2 (en) | Wavelength filter | |
| JP3006205B2 (en) | Optical fiber polarizer | |
| JPS63309906A (en) | Optical waveguide coupler | |
| JP2812469B2 (en) | Optical fiber type wavelength filter | |
| JPS6289003A (en) | Fiber type band pass/stop filter | |
| JP2805533B2 (en) | Fiber fusion type optical branch coupler | |
| JP2635720B2 (en) | Optical fiber coupler | |
| JPH0766086B2 (en) | Fiber type optical filter | |
| JPH02110409A (en) | Optical fiber coupler | |
| JPS58169124A (en) | Production of optical demultiplexer | |
| JP2778236B2 (en) | Waveguide-type optical multiplexer / demultiplexer and optical transmission module using the same | |
| JP2003222748A (en) | Optical waveguide type polarization splitting element and method of manufacturing the same | |
| JPH04322207A (en) | Optical fiber coupler and its manufacture | |
| JP2842968B2 (en) | Waveguide directional coupler |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| LAPS | Cancellation because of no payment of annual fees |